1. Field of the Invention
The present invention relates generally to pulsation dampeners, and more particularly to an elastomeric diaphragm for use in applications where such a dampener is exposed to a corrosive fluid and the diaphragm prevents the corrosive fluid from contacting the pressure vessel of the diaphragm.
2. The Related Art
Pulsation dampeners are typically connected in supply lines conveying fluid that is subject to surges or pulsations. For example, a reciprocating piston pump may be suitable for delivering hydraulic pressure, but creates undesirable pulsations in the process.
Such dampeners typically utilize flexible bladders or diaphragms for separating a pressure vessel into a compressible fluid zone and a zone for receiving the fluid subjected to pulsation. The diaphragm serves to dampen the pulsations as it moves back and forth in the pressure vessel. In some instances, metal inserts known as bridging disks or plates are carried by the diaphragm to provide additional support for the diaphragm at the region which covers pressure inlets.
U.S. Pat. No. 4,305,428, assigned to Hydril Co., the assignee of the present invention, describes a "surge absorber" wherein a pressurized compressible fluid, such as an inert gas, is introduced into an upper zone of a pressure vessel for absorbing pressure surges in a lower zone created by the process fluid in system flow lines. The diaphragm that separates the pressure zones includes a bridging disk that supports the diaphragm over both the process fluid inlet opening and an opening in an upper diaphragm support that permits entry of the compressible fluid into the upper zone. The bridging disk is partially encapsulated in the diaphragm, but exposes a threaded bore and a region of the disk surrounding the bore to the process fluid. Thus, the disk/diaphragm interface is exposed to the process fluid, permitting reactants in the fluid to attack the bond between the disk and the diaphragm and cause the disk to separate from the diaphragm over time. Once the disk separates, the diaphragm quickly fails without reinforcement and the pulsation dampener ceases to perform its intended function.
U.S. Pat. Nos. 4,299,253 and 4,186,776, also both assigned to Hydril Co., disclose similar structures for a pulsation dampener diaphragm, both of which include a bridging disk for supporting the diaphragm. In both of these patents, the disk and the disk/diaphragm interface are clearly exposed to the process fluid, even more so than in the '428 patent.
U.S. Pat. No. 3,674,053, also assigned to Hydril Co., discloses another similar structure to that described in the above mentioned patents, except the diaphragm of the '053 patent only covers a single fluid inlet. A bridging disk is partially encapsulated in the diaphragm, but the diaphragm again exposes a portion of the disk/diaphragm interface to the process fluid.
It is therefore an object of the present invention to identify the problem stated above, namely that exposure of a bridging insert in a pulsation dampener diaphragm to the harsh process fluid having the undesirable pulsation creates a risk that the bond between the disk and the diaphragm will deteriorate and cause the insert to separate from the diaphragm.
It is a further object of the present invention to provide a solution for this problem, in the form of completely encasing the bridging insert within the diaphragm to protect the bond between the disk and diaphragm from the process fluid so that the insert will not separate from the diaphragm.